Given cos a = -4/7 and sin b = 3/5, where a and b are not in quadrant 2, find the coordinates of p(a+b)?

Answer 1

I have no idea what "the coordinates of p(a+b)" is supposed to be.

We could find such values as
sin(a+b) or tan(a+b).

something like sinb = 3/5
has an infinite number of points associated with its end-points. They could be
P(4,3)
or Q(8,6)
or R(40,30)
etc

Please clarify